The objective of the proposed program of research is the development and application of new physical methods for the study of systems of biological importance. The new physical methods include: a) x-ray diffraction using a synchrotron radiation source, b) perturbed angular correlation of gamma radiation (PAC), c) extended x-ray absorption fine structure (EXAFS). These techniques will be applied to the study of diffuse diffraction from the membranes of myelin, the characterization of phospholipid vesicles, anomalous x-ray scattering effects in membranes, and the structural integrity of lipid vesicles in vivo. The availability of x-radiation of extremely high intensity from the synchrotron radiation source available at the Stanford Synchrotron Radiation Laboratory provides a unique opportunity to make structural measurements on systems of biological interest. The perturbed angular correlation of gamma radiation provides a labeling method for biological systems which yields infromation on molecular rotational correlation times with a sensitivity comparable to that of radioactive tracer techniques. Since the gamma-rays have reasonable penetration distances, the method can be applied to the study of molecular rotation and conformational changes in vivo. EXAFS can be applied to determine with great accuracy the distances of atoms bound to metal atoms located, for example, at the active site of macromolecules with important biological functions.